I've given up on houdini and quicktime a long time ago. Right now we're using a custom made flipbook OUT rop which uses ffmpeg to export quicktimes.
It's based on Platon Filimonov flipbook rop that he posted somewhere on the forums (or I found it here as well https://owlfx.wordpress.com/2011/03/25/flipbook-rop/), [owlfx.wordpress.com] but I've extended it to make video output with optional audio. It does however require ffmpeg to be in system path for it to work.
I'll clean the .otl of some custom production rubbish I have there and post it for others to use when I get to work on Monday.
If you have a script that runs ffmpeg, then you can have your own MVexport file and makes the script available from mplay's export menu to do this as well.